Trou sans Fond submarine canyon: Ivory Coast, Africa

Abstract

A bathymetric chart of the Trou sans Fond (Bottomless Hole) submarine canyon off the Ivory Coast, Africa, is presented, based upon a 1400-km survey in 1968 by the O.S.S. Discoverer. The canyon originates with a double head just off the beach and cuts a deep V-shaped furrow across the 30-km-wide shelf, attaining a maximum relief of 450 fm (823 m) near the shelf break. The canyon has a slightly sinuous and rugged relief down the continental slope, indicating an active erosional regime. At 1500 fm (2745 m) where the continental rise commences, the canyon is abruptly offset 20 km to the west, suggesting that the present outer fan valley is a newly developed channel. On the continental rise a depositional regime is indicated by well developed natural levees which have a cross-sectional area 60 times that of the Mississippi in the delta region. The Trou sans Fond appears to be the only canyon which taps the paralic zone between the Cayar Canyon to the north and the Congo Canyon to the south.